1. Field of the Invention
The present invention relates to a fuel supply device of an engine.
2. Description of the Related Art
In a known engine, the engine is provided with an assist air type fuel injector comprising a nozzle opening, an assist air passage connected to the nozzle opening, and a fuel valve for injecting fuel into the air assist passage. The assist air passage is connected, via an assist air supply control valve, to the intake passage at a point upstream of the throttle valve. The air pressure in the air assist passage and the vacuum in the intake passage downstream of the throttle valve are made to act on the fuel pressure regulator, to thereby regulate the pressure of fuel fed to the fuel valve. Namely, the pressure of fuel fed to the fuel valve is maintained at a pressure higher than the combined pressure of the air pressure and the vacuum by a fixed pressure, by the fuel pressure regulator (see Japanese Unexamined Utility Model publication No. 58-173767). In this engine, the amount of air fed to the assist air passage is controlled by controlling the opening operation of the assist air supply control valve.
In this engine, however, when the assist air supply control valve is opened or closed, pressure fluctuations are generated in the assist air passage downstream of the assist air supply control valve. At this time, the fluctuations of the pressure are transmitted to the fuel pressure regulator, and thus fluctuations occur in the above-mentioned combined pressure of the air pressure and the vacuum. As a result, fluctuations occur in the pressure of fuel fed to the fuel valve and thus a problem arises in that the amount of fuel injected from the fuel injector fluctuates relative to the regular amount, shortly after the assist air supply control valve is opened or closed.